Compact antenna test range equipment

ABSTRACT

A compact antenna test range equipment of the invention includes a microwave darkroom including a plurality of walls connected to each other, a reflector disposed in the microwave darkroom and comprising a reflecting surface having a polygon shape comprising a plurality of edges and a plurality of corners, each of the corners is located between two of the edges, wherein each of the corners aiming at one of the walls, a feeding antenna disposed in the microwave darkroom and corresponding to any position of the reflecting surface, and a test turning table disposed in the microwave darkroom and configured to bear a testing piece which is disposed in a quiet zone and exited by a plane electromagnetic wave. The feeding antenna transmits electromagnetic waves to the reflecting surface so as to generate a plane electromagnetic waves or receive electromagnetic waves from the quiet zone.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to antenna testing equipment, and moreparticularly to a compact antenna testing range equipment reducingscattering of electromagnetic wave to obtain electromagnetic waves withuniform amplitude and phase in a quiet zone.

Description of the Related Art

Characteristic tests such as general communication products or radarsmust be tested at a place where the signal source is far away, that is,where the electromagnetic wave that excites the object under test hasshown a form close to a uniform plane wave. But another test method isto use the Compact Antenna Test Range (CATR) Reflector, which uses thecompact antenna test field reflector. It corrects the phase wave frontby using the path difference of the electromagnetic wave reflected bythe compact curvature reflecting surface in the microwave darkroom, andcan generate electromagnetic waves in a short distance equivalent to theplane electromagnetic waves generated by long-distance propagation. Theuniformity of the amplitude and phase of the plane electromagnetic wavegenerated in the test quiet zone is the most important indication factorof the quality of CATR. Up to now, the compact antenna test rangeequipment is still known as a well applied and accurate test field forthe test of communication products or radars.

As shown in FIG. 1, an edge of the reflector of the CATR is eitherserrated edge or roll-edged, and the overall design shape issubstantially square or rectangular. Because the edge of the reflectoris parallel to the wall of the microwave darkroom, the electromagneticwaves reflected and scattered by the edge of the reflector willilluminate the walls with a larger energy and a larger incident anglewith respect to the normal direction of the absorbing material on thewall (the ceiling, the floor and the side walls), which generatesscattered electromagnetic waves, especially at lower operatingfrequencies. These scattered electromagnetic wave energy enters thequiet zone to interfere with the uniform plane electromagnetic wave(uniform plane wave) expected in the quiet zone and thus increases theamplitude ripple and phase ripple, whereby the accuracy of the test isaffected.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a compact antenna testing rangeequipment. The compact antenna testing range equipment can reduce theangle and energy of the electromagnetic waves reflected and scattered bythe edge of the reflecting surface of the reflector illuminates the wallof the compact antenna testing range equipment, so that the interferencewave (clutter) entering the test quiet zone is reduced, and the testquiet zone has a high-quality uniform plane wave (uniform plane wave).

The invention provides a compact antenna test range equipment. Thecompact antenna test range equipment in accordance with an exemplaryembodiment of the invention includes a microwave darkroom including aplurality of walls connected to each other, a reflector disposed in themicrowave darkroom and comprising a reflecting surface having a polygonshape comprising a plurality of edges and a plurality of corners, eachof the corners is located between two of the edges, wherein each of thecorners aiming at one of the walls, a feeding antenna disposed in themicrowave darkroom and corresponding to any position of the reflectingsurface, and a test turning table disposed in the microwave darkroom andconfigured to bear a testing piece which is disposed in a quiet zone andexited by a plane electromagnetic wave. The feeding antenna transmitselectromagnetic waves to the reflecting surface so as to generate aplane electromagnetic waves or receive electromagnetic waves from thequiet zone.

In another exemplary embodiment, the microwave darkroom has four walls,and the reflecting surface has a diamond shape having four corners.

In yet another exemplary embodiment, the reflecting surface has twodiagonal lines.

In another exemplary embodiment, the diagonal lines are perpendicularand have identical length.

In yet another exemplary embodiment, the walls have wave absorbingmaterial and wave absorbing structures.

In another exemplary embodiment, the feeding antenna transmits theelectromagnetic waves to a center of the reflecting surface, and thetesting piece aims at the center to be excited by the planeelectromagnetic waves.

In yet another exemplary embodiment, the feeding antenna and the testingpiece are disposed on the wall serving as a ground, and the reflectingsurface has an inclined angle with respect to the ground.

In another exemplary embodiment, the feeding antenna corresponds to oneof the corners of the reflecting surface near the ground.

In yet another exemplary embodiment, the feeding antenna corresponds toone lateral corner of the reflecting surface.

In another exemplary embodiment, the test turning table comprises arotating mechanism altering an angle of a normal line of the testingpiece with respect to wave front of the plane electromagnetic waves.

The compact antenna test range equipment of the prevent inventionincludes the reflector with the corners aiming at the wall of themicrowave darkroom. The electromagnetic waves reflected and scattered bythe corners of the reflector are weak, so the electromagnetic wavesincident on the wall of the microwave darkroom are relatively weak.Therefore, the scattered interference clutter generated by the wall isrelatively weak. The reflected and scattered electromagnetic wavesgenerated by the edge of the reflective surface are farther away fromthe wall of the microwave darkroom, and the energy illuminating to thewall is lower. It has a small off-normal angle of incidence and goodabsorption. Therefore, the scattered interference clutter is relativelyweak. Based on the above factors, it will not interfere with the qualityof the uniform plane electromagnetic wave in the quiet zone of the test.In addition, the electromagnetic waves reflected by the corners of thereflector to the turntable of the test piece located in the center ofthe test quiet zone are also weak, and the scattered interference wavesgenerated by the turntable mechanism are also much smaller. The compactantenna test range equipment of the present invention can also retainthe advantages of low interaction interference between the reflectedwave and the feed antenna in the conventional corner feed structure.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a perspective view of a conventional compact antenna testrange equipment;

FIG. 2 is a perspective view of an embodiment of a compact antenna testrange equipment of the present invention;

FIG. 3 is a schematic view of a reflector and a microwave darkroom ofthe compact antenna test range equipment of the present invention;

FIG. 4 is a schematic view of simulated electromagnetic field of thecompact antenna test range equipment of FIG. 6;

FIG. 5 is a side view of the compact antenna test range equipment ofFIG. 2;

FIG. 6 is a perspective view of another embodiment of a compact antennatest range equipment of the present invention;

FIG. 7 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 2.0 GHz generatedby the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 8 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 2.25 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 9 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 2.5 GHz generatedby the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 10 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 2.75 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 11 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 3.00 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 12 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 3.25 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 13 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 3.50 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 14 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 3.75 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 15 shows the test result of variation of the amplitude of the planeelectromagnetic wave in the quiet zone at frequency of 4.00 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 16 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 2.0 GHz generatedby the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 17 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 2.25 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 18 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 2.5 GHz generatedby the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 19 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 2.75 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 20 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 3.00 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 21 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 3.25 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 22 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 3.50 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 23 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 3.75 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface;

FIG. 24 shows the test result of variation of the phase of the planeelectromagnetic wave in the quiet zone at frequency of 4.00 GHzgenerated by the compact antenna test range equipment of FIG. 6 and theconventional compact antenna test range equipment shown in FIG. 1 in thesame-sized microwave darkroom and reflective surface.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

Please refer to FIG. 2, FIG. 3, FIG. 5, and FIG. 6, which show anembodiment of the compact antenna test range equipment of the presentinvention. The compact antenna test range equipment 100 of thisembodiment includes a microwave darkroom 10, a reflector 20, a feedingantenna 30, and a test piece turntable 40. The microwave darkroom 10includes a plurality of wall surfaces 11, 12, 13, 14 which are connectedadjacently. The wall surfaces 11, 12, 13, and 14 are provided withabsorbing materials and absorbing structures, such as pyramidalabsorbing materials and absorbing structures.

The reflector 20 is disposed in the microwave darkroom 10. The reflector20 has a polygonal reflecting surface 21, and the reflecting surface 21has a plurality of corners 211, and the corners 211 are arranged torespectively align with the wall surfaces 11, 12, 13, 14. In thisembodiment, the reflecting surface 21 is a diamond shape reflector withrespect to the floor and ceiling of the microwave darkroom 10. Thereflective surface 21 is a curved surface, such as a paraboloid. Thereflector 20 has a base 22, the reflecting surface 21 is carried by thebase 22, and the base 22 is set on the floor. In addition, as shown inFIG. 5, the reflective surface 21 of this embodiment has an inclinationangle with respect to the floor, which corresponds to the position ofthe feeding antenna 30. In another embodiment, as shown in FIG. 6, thereflecting surface 21 may not have an inclination angle, or may beinclined to the left or to the right. The reflecting surface 21 has twointersecting diagonal lines D1 and D2, and the diagonal lines D1 and D2of this embodiment have the same length. In this embodiment, the size ofthe reflecting surface 21 is 80 cm*80 cm, and the size of the test quietzone is 60 cm*60 cm.

As shown in FIGS. 2, 3, and 5, the feeding antenna 30 is arranged in themicrowave darkroom 10 and corresponds to any corner 211 of thereflecting surface 21. The feeding antenna 30 of this embodiment isarranged close to the floor and corresponds to the corner 211 of thereflective surface 21 close to the floor. The feeding antenna 30 is apoint wave source, which emits electromagnetic waves toward thereflecting surface 21, and then the electromagnetic waves are reflectedby the reflecting surface 21 to form a plane wave traveling to the testpiece 41 located in the test quiet zone 43 for the testing of the testpiece 41.

The test piece turntable 40 is arranged in the microwave darkroom 10with a distance from the reflector 20, and the test piece 41 isinstalled on the test piece turntable 40 and located in the test quietzone 43 to be excited by plane electromagnetic waves. The test pieceturntable 40 has a rotating mechanism 42 that changes the angle of thenormal line of the test piece 41 with respect to the planeelectromagnetic wave front.

The corners 211 of the reflecting surface 21 aims at the wall surfaces11, 12, 13, 14 of the microwave darkroom 10 so that the electromagneticwaves reflected and scattered by the corners 211 of the reflector 20 isrelatively weak. Therefore the electromagnetic waves incident on thewall surfaces 11, 12, 13, 14 of the microwave darkroom 10 are relativelyweak, so that the scattered interference clutter generated is relativelyweak. However, the large reflected and scattered electromagnetic wavesgenerated by the edge of the reflecting surface 21 are far away from thewall of the microwave darkroom 10. The energy illuminating the absorberon the walls 11, 12, 13, and 14 of the microwave darkroom 10 is lower,and it has a smaller off-normal incident angle which causes betterabsorption, so that the scattered interference clutter generated isrelatively weak. As a conclusion, the quality of the plane wave in thetest quiet zone 43 is maintained. Therefore, the electromagnetic wavesthat illuminate the walls 11, 12, 13, and 14 are aligned with the edgeof the conventional reflective surface. The reflected and scatteredelectromagnetic waves reflected to the wall surface of the microwavedarkroom are much weaker. Therefore, the scattered electromagnetic wavesgenerated by the illumination of the absorbing material are weakened.The formation of interference clutters is thus weaker.

Please refer to FIG. 6, which shows another embodiment of the compactantenna test range equipment 100 of the present invention. The feedingantenna 30 of the compact antenna test range equipment 100 of thisembodiment is arranged to correspond to the corner 211 on the lateralside of the reflecting surface 21. In this embodiment, the size of thereflecting surface 21 is 180 cm*180 cm, and the size of the test quietzone is 80 cm*80 cm.

As shown in FIG. 4, it is the result of the simulation of the reflectedand scattered electromagnetic wave intensity of the compact antenna testrange equipment 100 shown in the embodiment of FIG. 6. Theelectromagnetic wave intensity of the corner 211 close to the reflectingsurface 21 is weaker than other areas. For example, the electromagneticwave intensity simulated at the corner 211 is −18 dB˜−24 dB, and theelectromagnetic wave intensity simulated at0 the edge of the reflectingsurface 21 is −9 dB˜−12 dB.

The compact antenna test range equipment of the prevent inventionincludes the reflector with the corners aiming at the wall of themicrowave darkroom. The electromagnetic waves reflected and scattered bythe corners of the reflector are weak, so the electromagnetic wavesincident on the wall of the microwave darkroom are relatively weak.Therefore, the scattered interference clutter generated by the wall isrelatively weak. The reflected and scattered electromagnetic wavesgenerated by the edge of the reflective surface are farther away fromthe wall of the microwave darkroom, and the energy illuminating to thewall is lower. It has a small off-normal angle of incidence and goodabsorption. Therefore, the scattered interference clutter is relativelyweak. Based on the above factors, it will not interfere with the qualityof the uniform plane electromagnetic wave in the quiet zone of the test.In addition, the electromagnetic waves reflected by the corners of thereflector to the turntable of the test piece located in the center ofthe test quiet zone are also weak, and the scattered interference wavesgenerated by the turntable mechanism are also much smaller. The compactantenna test range equipment of the present invention can also retainthe advantages of low interaction interference between the reflectedwave and the feeding antenna in the conventional corner feed structure.

Please refer to FIGS. 7 to 15, which show the test results of thevariation of the amplitude of the plane electromagnetic wave at afrequency of 2.0 GHz-4.0 GHz in the test quiet zone (+40 cm˜−40 cm). Thesize of the reflecting surface of the present invention and theconventional one is of the same size and is tested in a microwavedarkroom of the same size. The test results are shown in FIGS. 7 to 15,wherein the solid line represents the test data of the compact antennatest range equipment of the present invention, and the dashed linerepresents the test data of the conventional compact antenna test rangeequipment. As shown in the figures, the variation of the amplitude ofthe electromagnetic wave of the compact antenna test range equipment ofthe present invention is smaller than that of the conventional compactantenna test range equipment. Please refer to FIGS. 16 to 24, which showthe test results of the phase variation of the plane electromagneticwave in the quiet zone (+40 cm˜−40 cm) at the frequency of 2.0 GHz-4.0GHz. The solid line represents the test data of the compact antenna testrange equipment of the present invention, and the dotted line representsthe test data of the conventional compact antenna test range equipment.As shown in the figures, the phase variation of the electromagnetic waveof the compact antenna test range equipment of this invention is smallerthan that of the compact antenna test range equipment. Therefore, thepresent invention does produce relatively weak scattering interferenceelectromagnetic waves, whereby the plane electromagnetic waves in thetest quiet zone are more uniform.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements (as would be apparent to thoseskilled in the art). Therefore, the scope of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

What is claimed is:
 1. A compact antenna test range equipment,comprising: a microwave anechoic chamber comprises a plurality ofsurfaces connected to each other; a reflector disposed in the microwaveanechoic chamber and comprising a reflecting surface having a diamondshape comprising four edges and four corners, each of the corners islocated between two of the edges, wherein each of the corners aiming atone of the plurality of surfaces; a feeding antenna disposed in themicrowave anechoic chamber and corresponding to any position of thereflecting surface; and a test turning table disposed in the microwaveanechoic chamber and configured to bear a testing piece which isdisposed in a quiet zone and exited by a plane electromagnetic wave;wherein the feeding antenna transmits electromagnetic waves to thereflecting surface so as to generate plane electromagnetic waves to thequiet zone or to receive electromagnetic waves radiating from the quietzone; wherein the reflector, the feeding antenna, and the test turningtable are located within an area defined by the plurality of surfaces ofthe microwave anechoic chamber; wherein each corner of the four cornersof the reflector is positioned to extend toward a corresponding surfaceof the plurality of surfaces of the microwave anechoic chamber; wherein,when each corner of the four corners of the reflector is positioned toextend toward the corresponding surface of the plurality of surfaces ofthe microwave anechoic chamber, the feeding antenna transmits theelectromagnetic waves to the reflecting surface so as to producerelatively weak scattering interference electromagnetic waves togenerate more uniform plane electromagnetic waves in the test quietzone, an interference wave entering the test quiet zone is reduced, andthe test quiet zone has high-quality uniform plane electromagneticwaves.
 2. The compact antenna test range equipment as claimed in claim1, wherein the microwave anechoic chamber has four surfaces.
 3. Thecompact antenna test range equipment as claimed in claim 2, wherein thereflecting surface has two diagonal lines.
 4. The compact antenna testrange equipment as claimed in claim 3, wherein the diagonal lines areperpendicular and have identical length.
 5. The compact antenna testrange equipment as claimed in claim 1, wherein the surfaces have waveabsorbing material and wave absorbing structures.
 6. The compact antennatest range equipment as claimed in claim 1, wherein the feeding antennatransmits the electromagnetic waves to a center of the reflectingsurface, and the testing piece aims at the center to be excited by theplane electromagnetic waves.
 7. The compact antenna test range equipmentas claimed in claim 1, wherein the feeding antenna and the testing pieceare disposed on the surface serving as a ground, and the reflectingsurface has an inclined angle with respect to the ground.
 8. The compactantenna test range equipment as claimed in claim 7, wherein the feedingantenna corresponds to one of the corners of the reflecting surface nearthe ground.
 9. The compact antenna test range equipment as claimed inclaim 7, wherein the feeding antenna corresponds to one lateral cornerof the reflecting surface.
 10. The compact antenna test range equipmentas claimed in claim 1, wherein the test turning table comprises arotating mechanism altering an angle of a normal line of the testingpiece with respect to wave front of the plane electromagnetic waves.